Film driving mechanism



July 16, 1935- I G. P. REGAN 2,008,402

FILM DRIVING MECHANI SM Filed Feb. 19, 1934 DO U ODD

INVENTOR. $91 04 7.

wawmwwofzw I ATTORNEYS.

Patented July 16, 1935 UNITED STATESP-ATENT OFFICE This invention relates to a method of imparting movement to'a film by vacuum action, and'to a mechanism whereby a film is positively gripped and secured to a driving member by vacuum action.

Deterioration of the film, such as used in motion pictures, talkies, etc., usually depends upon theawear produced in the perforations formed in the side edges of the This wear is caused by the sprocket gears-over which the film passes and by the feeding pawls imparting movement to the film. In sound or talking films this wear is very detrimental as it causes a slight lost motion or flutter which causes sound distortion and flicker in the picture proper. Wear and tear of the perforations also cause the film to slip or jump one or more sprocket teeth, thereby getting the picture out of frame, in fact, many other objections could be mentioned but as they are common knowledge to the profession the objections already mentioned should suffice.

The object of the present invention is to generally improve and simplify the construction and operation of driving mechanisms of the character described, and particularly to provide a vacuum drive for films whereby movement either continuously or intermittently may be imparted to the film without the slightest slippage, flicker, lost mention or vibration.

The invention more specifically stated com;- prises a hollow perforated drum around which the film passes, means for maintaining a partial vacuum of the drum to cause-the film to adhere to the surface of the drum, and means for driving the drum and the film carried thereby.

The invention is shown by way of illustration in the accomg drawing, in which-- Fig. 1 is a central vertical sectional view of the invention.

Fig. 2 is a side elevation of the driving drum.

Fig. 3 is a diagrammatic iront view of the driving drum and the guide rollers used in conjunction therewith.

Referring to the drawing in detail, and particularly Figs. 1 and ii, A indicates a hollow drum secured to a. shaft 2, which will hereinafter be referred to as the driving shaft. This shaft may be driven in any suitable manner, either intermittentb or continuously, depending upon. the use to which the drive is put. The film to be driven, and indicated at 2B, is wrapped around the exterior surface of the drum, as shown in Figs. 1 and 3, and it is held in position by guide rollers generally indicated at 8 and 3a. The surface of the drum is perforated, as shown at 2 Claims. (01. it'll-2.3)

The ineans for maintaining a partial vacuum in the drum may be a pump, or the 1ike, generally indicated at C. The suction side of the pump is indicated at 5 and is connected with the drum through the tubular connections indicated at G, I and 8. A tight running joint is maintained between the connection 8 and the drum so as to reduce leakage to a minimum.

The film drive shown in the present instance may be employed in conjunction with cameras, projecting machines, recording machines, printing machines, cutting machines, marking machines, re-recording machines; in fact in any machine where a film of this character is employed for any purpose whatsoever. It is for this reason that a specific form of drive is not shown as the shaft 2 driving the drum may be intermittently driven in certain types of machines and continuously in others. With the film wrapped about the driving drum, as shown in Fig. 3, a large vacuum or suction surface is presented toward the film and the film is for this reason positively gripped so that the danger of slippage, flicker, lost motion, or vibration is entirely eliminated. Furthermore, as the perforated side edges of the film, indicated at it, are not employed for driving purposes the wear and tear thereon will be re-' duced to a minimum and even though the perforations should be worn it would not be detrimental either to the reproduction of sound pictures, or otherwise, as the driving mechanism here disclosed does in no way depend upon the perforations for driving purposes.

While certain features of the present invention 1 are more or less specifically described, I wish it understood that various changes may be resorted to within the scope of the appended claims. Similarly, that the materials and finish of the several parts employed may be such as the manufacturer may decide, or varying conditions or uses may demand.

Having thus described my invention, what I claim and desire to secure by Letters Patent is--' 1. In an apparatus employing a film of the character described, a driving shaft, a hollow drum secured to and driven by the shaft, said drum having a peripheral face 'to receive and support the film and said drum being open at one end, a stationary cover plate for the open end of the drum and i a substantially air-tight fit with the rotating drum, a pipe connected with the cover plate and communicating with the interior of the drum, said pipe being connected with a vacuum producing means, and a plurality of perforations formed in the film supporting surface of the drum to cause the film to adhere to the surface of the drum when vacuum is applied, said perforations being arranged in spaced rows transversely of the drum and on an angle with relation to the longitudinal axis of the film and in a position where no row overlaps another.

2. In an apparatus employing a film of the character described, a driving shaft, a hollow drum secured to and driven by the shaft, said drum having a peripheral face to receive and support the film and said drum being open at one end, a stationary cover plate for the open end of the drum and forming a substantially air-tight fit with the rotating drum, a pipe connected with the cover plate and communicating with the interior of the drum, said pipe being connected with a vacuum producing means, a plurality of perforations formed in the film supporting surface of the drum to cause the film to adhere to the surface of the drum when vacuum is applied, andia pair of guide pulleys disposed one at each side of the drum, said film passing over said guide pulleys and over the driun and being so positioned that the film will surround approximately threequarters of the periphery of the drum and leave the remaining quarter exposed for the admission of air so as to reduce the vacuum at the points where the film engages and leaves the drum.

GEORGE P. REGAN. 

